Abstract Background and Objectives: Cuminum cyminum L. (green cumin) is one of the most important medicinal and spice plants, with a wide genetic diversity in Iran. This diversity, expressed in physiological, metabolic, and agronomic traits, provides valuable resources for breeding programs aimed at enhancing yield, quality, and stress tolerance. The present study aimed to compare ten native Iranian cumin ecotypes in terms of antioxidant capacity, secondary metabolites, and agronomic traits, in order to identify superior genotypes for targeted breeding and medicinal exploitation. Materials and Methods: This study was conducted during the 2023–2024 growing season at the Experimental Farm of the Research Technology Institute of Plant Production, Afzalipour Research Center, Shahid Bahonar University of Kerman. The experiment was laid out in a randomized complete block design with three replications. Ten native cumin ecotypes (Esfarayen, Bardaskan, Khansar, Ardestan, Sepidan, Sivand, Sirjan, Mahan, Bardsir, and Rafsanjan) collected from different provinces of Iran (North Khorasan, Razavi Khorasan, Isfahan, Fars, and Kerman) were evaluated under uniform agronomic conditions including land preparation, planting, irrigation, weed control, and harvesting. Throughout the growing season, sampling and trait measurements were conducted using standardized procedures. Evaluated traits included seed yield per hectare, essential oil content (%), essential oil yield (calculated as seed yield × essential oil content), cuminaldehyde percentage, total protein content, total phenolics, and total anthocyanins. Activities of antioxidant enzymes (superoxide dismutase (SOD), catalase (CAT), guaiacol peroxidase (GPX), and ascorbate peroxidase (APX)) were also assayed using conventional enzymatic methods. Data were analyzed using analysis of variance (ANOVA) to assess ecotype effects, Pearson correlation to determine relationships among traits, stepwise regression to identify key predictors of seed yield, and principal component analysis (PCA) to explore trait variation patterns and ecotype differentiation. Results: Analysis of variance revealed significant differences among the ecotypes for all studied traits, indicating substantial genetic diversity within native Iranian cumin. The Esfarayen ecotype exhibited the highest seed yield, exceeding the lowest-yielding ecotype, Sirjan, by 111%. However, Esfarayen had the lowest total phenolics and protein content. The Mahan ecotype stood out with the highest essential oil content and essential oil yield among all ecotypes, whereas Bardsir showed the highest total anthocyanin levels. Rafsanjan exhibited the highest total phenolics and activities of guaiacol peroxidase and ascorbate peroxidase but had the lowest catalase and superoxide dismutase activities. Conversely, Sepidan showed the highest catalase and superoxide dismutase activities. Significant negative correlations were observed between protein content and CAT and SOD activities. Additionally, essential oil content negatively correlated with anthocyanin levels, and cuminaldehyde content was negatively correlated with total protein, suggesting metabolic pathway trade-offs in the synthesis of these compounds. Stepwise regression identified four key traits as significant predictors of seed yield: essential oil content (17%), cuminaldehyde percentage (14%), APX activity (10%), and SOD activity (9%), collectively explaining 50% of the variation in seed yield. PCA revealed that the first two principal components accounted for 61.20% of the total trait variation, effectively differentiating the Mahan, Esfarayen, Sepidan, and Rafsanjan ecotypes based on their combined performance and biochemical profiles.
Conclusions: The results highlight a rich pool of genetic and biochemical diversity among Iranian cumin ecotypes, which can be exploited to develop high-yielding, high-quality, and stress-tolerant cultivars. Esfarayen, Mahan, Rafsanjan, and Sepidan emerged as promising candidates for breeding programs, each combining specific desirable traits. The findings also emphasize that improving EO yield in cumin is more effectively achieved through enhancing seed yield rather than increasing EO percentage alone. These outcomes underline the necessity of multi-objective breeding approaches to balance productivity, phytochemical composition, and resilience in medicinal and aromatic plants. |